trace: better manage the context info for events
Impact: make trace_event more convenient for tracers
All tracers (for the moment) that use the struct trace_event want to
have the context info printed before their own output: the pid/cmdline,
cpu, and timestamp.
But some other tracers that want to implement their trace_event
callbacks will not necessary need these information or they may want to
format them as they want.
This patch adds a new default-enabled trace option:
TRACE_ITER_CONTEXT_INFO When disabled through:
echo nocontext-info > /debugfs/tracing/trace_options
The pid, cpu and timestamps headers will not be printed.
IE with the sched_switch tracer with context-info (default):
bash-2935 [001] 100.356561: 2935:120:S ==> [001] 0:140:R <idle>
<idle>-0 [000] 100.412804: 0:140:R + [000] 11:115:S events/0
<idle>-0 [000] 100.412816: 0:140:R ==> [000] 11:115:R events/0
events/0-11 [000] 100.412829: 11:115:S ==> [000] 0:140:R <idle>
Without context-info:
2935:120:S ==> [001] 0:140:R <idle>
0:140:R + [000] 11:115:S events/0
0:140:R ==> [000] 11:115:R events/0
11:115:S ==> [000] 0:140:R <idle>
A tracer can disable it at runtime by clearing the bit
TRACE_ITER_CONTEXT_INFO in trace_flags.
The print routines were renamed to trace_print_context and
trace_print_lat_context, so that they can be used by tracers if they
want to use them for one of the trace_event callbacks.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index e603a29..f0c7a0f 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -405,6 +405,10 @@
struct trace_entry *tracing_get_trace_entry(struct trace_array *tr,
struct trace_array_cpu *data);
+
+struct trace_entry *trace_find_next_entry(struct trace_iterator *iter,
+ int *ent_cpu, u64 *ent_ts);
+
void tracing_generic_entry_update(struct trace_entry *entry,
unsigned long flags,
int pc);
@@ -591,7 +595,8 @@
TRACE_ITER_ANNOTATE = 0x2000,
TRACE_ITER_USERSTACKTRACE = 0x4000,
TRACE_ITER_SYM_USEROBJ = 0x8000,
- TRACE_ITER_PRINTK_MSGONLY = 0x10000
+ TRACE_ITER_PRINTK_MSGONLY = 0x10000,
+ TRACE_ITER_CONTEXT_INFO = 0x20000 /* Print pid/cpu/time */
};
/*